html, body {
  height: 100%;
  width: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
.wave {
  position: absolute;
  left:0;
  right:0;
  top:0;
  padding-top:35%;
  bottom:0;
  z-index: 1;
}
.wave + .wave {
  z-index: 2;
}